This is a more interesting question that it might seem. For a Sunday afternoon read, please take a look to Jonesforth [1] for an implementation of a basic Forth for Linux/32 bits. It's written in literate style and it reads like a nice book.

If you are not that interested in the implementation of the compiler (and if so you might be missing the ultimate point of Forth), Starting Forth [2] is a classic resource.

Edit: formatting

[1] https://github.com/AlexandreAbreu/jonesforth

[2] https://www.forth.com/starting-forth/